Abu Dhabi Commercial Bank — false terms and hidden charges!

I opened a Meethaq fixed deposit account with this bank in January 2008. After 8 months of depositing AED 2000 I decided to pull the money back and close this fixed deposit. The bank ignored my request for 3 weeks and then claimed that the money I deposited total of AED 16, 000 is no longer available as they lost the investments. Then they claimed that because of the terms I lost this amount. Now after 7 years am receiving that I owe the bank AED 8830 on a debt card that had no outstanding balance! Is there a way I can claim my money back and complain to the authorities of their false practices.